Piston container



FIG. 1 is a perspective view of a piston container showing my new design;

FIG. 2 is a front elevational view thereof, the rear being a mirror image;

FIG. 3 is a right side elevational view thereof, the left side being a mirror image;

FIG. 4 is a top plan view thereof; the broken lines in FIG. 4 are included for the purpose of illustrating a portion of the piston container that forms no part of the claimed design; and,

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a piston container, as shown and described. 